Light projecting system



Why 19, 1936.

T. LINDENBERG ET AL LIGHT PROJECTING SYSTEM 2 Sheets-Sheet l Filed Nov. 20, 1954 May 19, 1936. T. LINDENBERG ET AL.

LIGHT PROJECTING SYSTEM 2 Sheets-Sheet 2 Filed Nov. 20, 1934 7% J Z? 3W6 r 0 m@% f; T

Patented May 19, 1936 LIGHT PROJECTING SYSTEM Theodore Lindenberg and Theodore Lindenberg, J12, Columbus, Ohio Application November 20, 1934, Serial No. 753,950

3 Claims.

This invention relates to improvements in light projecting systems and has particular reference to a novel method and means by which a beam of light emanating from a single source,

-may be intercepted and reflected to produce a plurality of spaced beams which may be directed in a controlled manner toward different points.

The invention is more specifically concerned with the projection of motion pictures in theater buildings employing dual auditoriums whereby 5, 1934, there has been disclosed a system of.

mirrors arranged to intercept a light beam issuing from a motion picture projecting machine whereby to divert the light beam and divide the same into two or more beams traveling in different directions. It is a particular object of the present invention to utilize the general features of the invention set forth in the aforesaid application but, in addition, to modify the formation and locations of the light reflecting mirrors to the end of enabling the light projected on the spaced screens of the auditoriums to be of uniform intensity over the full illuminated areas of said screens.

For a further understanding of the invention, reference is to be had to the following description and the accompanying drawings, wherein:

Fig. 1 is a horizontal sectional view taken through a theater building equipped with dual auditoriums and utilizing the light projecting system comprising the present invention;

Fig. 2 is a similar view on a larger scale disclosing the arrangement of the light reflecting mirrors comprising the present invention by which light from a single source is divided to produce a plurality of beams which are directed toward the screens of said auditoriums;

Fig.- 3 is a perspective view of the plain and apertured mirrors utilized by the present invention;

Fig. 4 is a front elevationof the apertured mirror;

Fig. 5 is a similar view of the plain mirror;

Fig. 6 is a vertical sectional View taken through the apertured mirror on the line VIVI of Fig. 4.

In Fig. 1, the outer walls of the theater building have been designated by the numeral l, the

numeral 2 designates a central or divisional wall which divides the building into a plurality of auditoriums 33. In the front of each auditorium there is arranged a motion picture display screen or other equivalent surface 4 upon which 5 motion pictures are adapted to be projected. In the rear of the building, there is formed the usual projection room 5 in which is received one or more standard motion picture projection machines 6. It will be understood that in motion picture theaters two projection machines are employed and which are used alternately for the purpose of producing a continuous display of motion picture reels; However, for the sake of clearness, but one of such machines has been disclosed.

The light projecting lens barrel of the projecting machine is designated by the numeral 1 and from which issues the customary strong beam of light which for a short distance in front of the projecting machine is substantially round or circular in cross section, the said beam of light being designated in Fig. 2 by the reference charactor a. Arranged in the path of projection of the light beam a, in the specific embodiment of the invention here under consideration, are apertured and plain mirrors 8 and 9 respectively. In this instance, the mirrors are spaced relatively approximately 90 apart and are arranged in the principal axis of the beam a. If desired, the mirrors may be removably mounted within a casing l0, supported in connection with the front wall of the projection room 5, the said casing being formed with an opening ll through which the beam a passes.

In order to obtain uniform intensity of iilumination over the full light receiving areas of the screen 4, we have found it necessary to utilize an unusual arrangement of silve'red surfaces on the mirror 8. It will be noted that the apertured mirror. is disposed at an angle of approximately 45 to the principal axis of the beam 11 and that this beam is substantially circular in cross sectional formation when projected on the surfaces of said mirror and therefore in order that the light beams b and c reflected from the surfaces of both the mirrors 8 and 9, in paths substantially 90 to the principal axis. of the beam a, will be of uniform cross sectional intensity, and to avoid light and dark areas on the screens 4, we have constructed the mirror 8 to include a plurality of spaced diverging clear glass slots or apertures [2 which are spaced or separated by corresponding mirror strips l3, the said strips and apertures increasing in width or transverse thickness from the left toward the right edge of the glass plate constituting the mirror body.

By this arrangement, light incident on the strips l3 will be reflected to produce the beam b while those rays of the beam 41 which are not intercepted by the mirrored strips l3 will pass through the apertures I2 and will be intercepted I by the surface of the plain mirror 9 so as to reflect the same to produce the beam which advances i in a direction directly opposed to that of the beam b. Moreover, since the apertured mirror is arranged at a 45 angle to the axis of the beam 11 and since said latter beam is substantially circular in cross section, the said beam when contacting with the mirror 8 possesses a non-circular configuration of substantially the formation indicated by the dotted lines d in Fig. 4. The angular arrangement of the alternate apertures l2 and the strips l3 of the mirror 8 adapts said mirror to the cross sectional configuration of the light beam 11 as indicated at d so that light rays of uniform intensity will pass through the apertures l2 and will be reflected from the surfaces of the mirror 9 to comprise the beam 0.

The beams 12 and c are projected toward mirrors I I and I respectively arranged in the ends of the casing ID at angles of substantially 45 with respect to the principal axes of the beams b and 0, whereby light beams e and 1 will be refiected respectively from said mirrors It and I5 through registering openings l5, formed in the ends of the casing in and the front wall of the projection room, in order that said beams e and I may be directed upon the picture displaying screens 4 of the auditoriums 3. The mirrors I4 and I5 are somewhat larger than the mirrors 8 and 9 in order to compensate for the increase in cross sectional area of the beams b and 0 during 0 travel of the latter from the mirrors 8 and 9 to evenly and uniformly illuminating each of a plurality of spaced screens from a single source of light projection. In the aforesaid application, of which the present application constitutes a continuation-in-part, there has been disclosed a system of projecting light by which two or more screens may be simultaneously illuminated from a single source of light projection. However, by the present disclosure, a further and very important improvement is efiected in obtaining uniform increments of illumination over the full light receiving areas of such screens.

What is claimed is:

1. In a motion picture projecting system, the combination with a pair of parallel adjoining auditoriums, apparatus for projecting a primary beam of light through a motion picture film, a screen interceptingsaid primary light beam and disposed in angular relationship to its principal axis, said screen comprising a plurality of spaced mirrored light-reflecting areas running trans-' versely of the mirror in increasing width and intervening non-reflecting light-transmitting areas corresponding thereto, said mirrored areas producing a secondary light beam projected in a,

course substantially at right angles to that of the primary light beam, an angularly disposed mirror for receiving the non-reflected light rays of the primary beam following passage of the latter through the non-reflected light-transmitting areas of said screen, the angularity of said lastnamed mirror producing a tertiary light beam projecting substantially at right angles to the axis of the primary beam and in an opposed direction to'that of the secondary beam, and angularly disposed mirrors intercepting the secondary and tertiary beams and reflecting the latter longitudinally through said auditoriums.

2. In a motion picture projecting system, the combination with a pair of parallel adjoining auditoriums, apparatus for projecting a primary beam of light through a motion picture film, a screen intercepting said primary light beam and disposed in angular relationship to its principal axis, said screen comprising a plurality of spaced mirrored light-reflecting areas running transversely of the mirror in increasing width and intervening non-reflecting light-transmitting areas corresponding thereto, said mirrored areas producing a secondary light beam projected in a course substantially at right angles to that of the primary light beam, an angularly disposed mirror for receiving the non-reflected light rays of the primary beam folowing passage of the latter through the non-reflected light-transmitting areas of said screen, the angularity of said lastnamed mirror producing a tertiary light beam projecting substantially at right angles to the axis of the primary beam and in an opposed direction to that of the secondary beam, angularly disposed mirrors intercepting the secondary and tertiary beams and reflecting the latter longitudinally through said auditoriums, and screen means disposed at the forward ends of the auditoriums to intercept the lightbeams projected through the latter.

3. In a motion picture projecting system, apparatus for projecting a primary beam of light through a motion picture film, a screen intercepting said light beam and disposed in angular relationship thereto, said screen comprising a plurality of spaced mirrors of strip formation running transversely of the mirror in increasing width and intervening non-reflecting light-transmitting areas of corresponding formation, said strips converging toward one side of said screen, the mirrored areas of said screen producing a secondary light beam projected in a course substantially at right angles to that of the primary light beam, an angularly disposed mirrorfor receiving the non-reflected light rays of the primary beam following passage of the latter through the non- THEODORE LINDENBERG. THEODORE LINDENBERG, JR. 

